WHAT'S UP DOC? Treacher Collins syndrome

Q: My neighbor just had the most adorable baby, and she was diagnosed with Treacher Collins syndrome. What is that?

A: Treacher Collins syndrome (TCS) is a genetic disorder that affects about one in every 25,000 to 50,000 births in the United States. It affects males and females, and all races, essentially equally.

TCS, also called mandibulofacial dysostosis, is a disorder that affects the development of the bones and other tissues of the face and head. In some patients these changes can be very subtle, other times they are more pronounced, and in some patients the bone/soft tissue can be affected severely enough to compromise breathing and/or eating at birth.

The specific developmental manifestations of abnormal facial features in a TCS patient are quite variable. The very common changes include a downward slanting of the eyes (away from the nose), a notch in the lower eyelid, abnormal ear formation, a small jaw and chin, underdeveloped cheekbones, a paucity of eye lashes (especially on the bottom), and other abnormalities. The skull bones may also be involved. About a third of TCS patients have a cleft palate or cleft lip (during formation the left and right sides of the roof of the mouth and/or the lip do not fuse together normally). In patients with severe ear development abnormalities, conductive hearing may be compromised. In those with severe eye involvement, vision loss can occur.

Over half the cases of TCS are from new gene mutations where there is no family history of the condition. However, TCS is also known to be an inherited condition. In some cases it inherited in an autosomal dominant fashion (getting one affected gene from either parent is sufficient to have the condition manifest), and in some cases in an autosomal recessive manner (an affected gene must be inherited from each parent in order for the condition to manifest). However the gene mutation occurs, the affected genes have been identified to be the TCOF1, POLR1D or POLR1C gene, and the defects in these genes cause the normal bone and soft tissue growth to be compromised starting at six to seven weeks of embryonic development.

TCS is usually diagnosed based on the facial physical features in the affected patient. Sometimes these changes are noted on a prenatal ultrasound. Since the genetics of the syndrome are reasonably well understood, genetic testing may confirm the diagnosis, and sometimes identifies the syndrome in relatives when family testing is felt to be indicated.

There are no specific medical treatments for TCS. If a newborn with TCS has airway compromise, immediate interventions to support their breathing may be needed. Similarly, if feeding is compromised, a feeding tube and/or other nutrition support may be needed. Surgeries to address these issues in a more permanent manner may be indicated during the first couple of years of life.

Imaging (CT scan, MRI and/or x-ray) to identify the specific manifestations in each patient will help inform what surgery may be of benefit. The specific surgery required, and the timing of it, is determined on a case by case basis. Cleft palate surgery is usually performed just prior to the child’s first birthday, although the timing of this may be delayed if there are airway or other concerns. Correction of ear anomalies is usually done around age 6 when the child’s rib cartilage (which is often used as graft tissue) is mature enough. It is difficult to obtain good results for ear reconstruction, and the surgery to do this may be done in several stages. Surgery for the jaw/chin is usually done in the early teens to allow for appropriate maturity of the development of the dental and jaw skeletal structures. Other facial surgery, possibly using bone grafts from other bones of the child’s body, may be needed as well.

Patients with TCS usually have normal intellectual development, and have a normal life expectancy. Surgery and other interventions are done to improve their quality of life, and to give positive psychosocial benefits. Support for families and friends is also important, as is teaching for the general public to improve their understanding of this condition (and of many of the other congenital conditions that may cause facial anomalies).